In the moments after the alleged confession, the witness said she attacked McCook with a bottle – but did not mention to police why she had assaulted him in subsequent interviews.

Mr Moffatt (right) was attacked as he was walking home along the Railway Road area of Coleraine after buying a newspaper in January 2001.

He was stabbed once in the stomach and died in hospital two months later on March 19.

Mr McCook (43), from Stonemill Terrace in Stockport but originally from Northern Ireland, was arrested in Cheshire last month.

Ms Brown, who is a witness for the prosecution, said she had known the defendant since he was a teenager when he was fostered in her parent's house and "loved him like a brother".

She said she bumped into Mr McCook at a pub in January 2006 and then went on to the party at her cousin's house.

Ms Brown said he had asked if he could tell her something.

He first began telling her in the kitchen and then in the living room.

"He told me he had stabbed Norman Moffatt, and he had died alone in hospital," she said.

"Then he kept saying it all the time," she said.

"I really did crack up. I was sort of stunned. I said I didn't believe it. I couldn't believe it.

"He had no expression on his face. It wasn't the same James that I knew."

Giving evidence, she told the prosecution barrister she had been "shocked and hurt" by what he had said and then attacked him.

"I lifted a bottle and split him open with it," she said.

She claimed he told her he was sorry and "asked to forgive him and all".

Ms Brown was arrested hours later for the assault and interviewed for four hours.

However, she did not mention the alleged confession to the murder during this time.

Three months later, on April 14 2006, she told the police but failed to sign the statement for a further six-and-a-half years – until October 2012.

Under cross-examination, defence barrister Arthur Harvey QC asked why she did not tell the police about the alleged confession after being arrested.

"I didn't know what was going on," she said. And she described it as "touting" to police.

Under further questioning she later said she did not tell the police for a number of months "because I wasn't a police informer".

Again Mr Harvey said she had given a "bag full of reasons" for not telling the police.

"In those three months why did you not go to the police?" he said.

Mr Harvey put to her: "Mr Moffatt was left to die in the streets of Coleraine and you have information on the murder.

"The murder was notorious in the Portrush and Coleraine area and you just decided you did not like informers?" he said.

"No, that's wrong," she said. "Who would have believed me?"

She later said that she "knew" she should have gone to the police earlier. Under further questioning Ms Brown said that: "From 2006 until now I've been to hell and back. I can't remember each wee specific thing."